Leishmania are protozoan parasites responsible for a spectrum of fatal and debilitating disease affecting at least 150 million people all over the world. No effective vaccine or efficient diagnostic tests are available, although they are greatly needed for disease management. Leishmania donovani causes visceral leishmaniasis (VL) which can be fatal if not promptly treated and early diagnosis is essential for it. Cutaneous leishmaniasis (CL) is characterized by non-diagnostic ulcers at the site of primary inoculation of the parasite by the sandflies. The most common cause of CL is L. major. Mucosal leishmaniasis is a late sequela, occurring in 1-3% of patients with CL. This proposal is designed to identify sensitive and specific serodiagnostic antigens which distinguish L. donovani and L. major infections. Recombinant antigens and synthetic peptides will be evaluated in an ELISA using sera from patients with VL and CL. Intradermal skin tests which are also very important for diagnosis will be included to the study. Leishmanial antigens that stimulate cellular immune response during skin test will be evaluated in vitro using patient T cells. Leishmanial antigens have recently become available primarily through Dr. Reed 's laboratory. We now have the ability to evaluate specific cellular and serological responses. Specific responses can be used to design diagnostics and vaccines. The use of recombinant leishmanial antigens is the focus of this proposal. Specifically rK39 and M15 will be evaluated as serodiagnostics using sera from Turkey and neighboring regions. For cellular responses we will evaluate LeIF, Ldp23, Lt1 and M15 by measuring cytokine and proliferative responses of PBMC from active and cured patients from Turkey and other regions. In particular, we will evaluate the role of IL-12 in these responses. Thus, advanced immunological methodologies will be applied to address practical issues in leishmaniasis. Thus, evaluation of leishmanial antigens to develop a vaccine for L. major or using antigens to stimulate curative immune responses is becoming extremely important. This product would have wide application and could be produced at a cost that would be affordable in the developing countries.